2011 Arthur H. Compton Award Announced by APSUO

APRIL 21, 2011

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The 2011 Compton Award winners. Clockwise from top left: Farrel Lytle, John Rehr, Edward Stern, and Dale Sayers.

The U.S. Department of Energy’s Advanced Photon Source (APS) and the APS Users Organization (APSUO) announce that the 2011 Arthur H. Compton Award will be presented jointly to Edward Stern, Farrel Lytle, Dale Sayers (posthumously), and John Rehr for their development of the technique of x-ray absorption fine structure spectroscopy (XAFS), whereby information can be acquired on local structure and on unoccupied electronic states in non‐crystalline materials. These outstanding scientists have defined how x-ray absorption fine structure spectroscopy (XAFS) is understood, enabling its application to an extremely wide range of problems across all disciplines of the physical, chemical, and biological sciences.

As a result of work by Stern, Lytle, Sayers, and Rehr, researchers at universities, national laboratories and industry using the APS can take XAFS and use it to solve and understand complex problems in materials research. “Thanks to the contributions of the nominees, the spectroscopy is understood and the theory is understood, so we can use it to its full capability to solve real-world problems,” said Simon R. Bare, a research fellow at UOP, a Honeywell Company.

Stern, together with Lytle and Sayers, developed the modern theory of XAFS in 1970. This theory describes XAFS as due to the scattering of the photoelectron ejected from an atom when it absorbs an x-ray. By Fourier-transforming the XAFS oscillations, Stern, Lytle, and Sayers showed that the phenomenon was sensitive to the local atomic structure around the absorbing atom and how XAFS can be used to retrieve quantitative information on interatomic distances and coordination around selected absorbing atoms. This established XAFS as a premier tool for probing short range atomic order in solids and liquids alike.

With the modern form of the XAFS equation in hand, Stern, Lytle, and Sayers, together with generations of students, proceeded to develop the basic experimental and analysis procedures for XAFS data collection and interpretation, many of which are still used today. As a result, XAFS has emerged as a powerful technique on a par with the more established diffraction probes. Their careful experiments, first using laboratory x‐rays and later at synchrotrons laid the groundwork for virtually all subsequent measurements. They showed an entire generation how to collect accurate data and helped to set the direction for all major experimental advances in the technique.

Rehr significantly extended the initial XAFS theories, and together with Robert Albers of Los Alamos National Laboratory, developed techniques for quantitative calculations. Perhaps most importantly, Rehr and his group developed a suite of programs that made ab initio calculations of XAFS spectra a practical reality. Rehr’s FEFF program (named after feff, the effective curved wave scattering amplitude in the modern XAFS equation) revolutionized the practice of XAFS. It is now possible to obtain very accurate calculations of the expected XAFS for a completely unknown structure, and thus to analyze experimental measurements in terms of the structure and other properties of a material.

The ability to quantitatively interpret XAFS measurements has profoundly impacted a huge range of scientific disciplines, and consequently XAFS and related spectroscopies are among the more commonly used synchrotron tools, with large and diverse user communities at most synchrotron sources, including the APS. In addition, the theoretical understanding of XAFS as a scattering phenomenon influenced the development of other modern synchrotron-based techniques such as x-ray photoelectron diffraction from surfaces, bulk x-ray holography, resonant x-ray scattering and inelastic x-ray scattering, as well as electron-based techniques such as electron energy loss spectroscopy.

Selected References

“New Technique for Investigating Noncrystalline Structures: Fourier Analysis of the Extended x-ray—Absorption Fine Structure,” Sayers, D.E., Stern, E.A. & Lytle, F.W., Phys. Rev. Lett. 27, 1204-1207 (1971).

“Theory of the Extended x-ray-Absorption Fine Structure,” Stern, E., Phys. Rev. B 10, 3027-3037 (1974).

“Extended X-ray-Absorption Fine-Structure Technique. II. Experimental Practice and Selected Results,” Lytle, F., Sayers, D. & Stern, E.,

Phys. Rev. B 11, 4825-4835 (1975).

“Extended X-ray Absorption Fine-Structure Technique. III. Determination of Physical Parameters,” Stern, E., Sayers, D. & Lytle, F., Phys. Rev. B 11, 4836-4846 (1975).

“Theoretical X-ray Absorption Fine Structure Standards,” J.J. Rehr, J. Mustre de Leon,

S.I. Zabinsky, and R.C. Albers, J. Am. Chem. Soc. 113, 5135 (1991).

“Scattering-matrix Formulation of Curved-wave Multiple-scattering Theory: Application to X-ray Absorption Theory,” J.J. Rehr and R.C. Albers, Phys. Rev. B 41, 8139 (1990).

About the Award

The Arthur H. Compton award was established in 1995 by the APS Users Organization to recognize an important scientific or technical accomplishment at the US Department of Energy’s Advanced Photon Source.

Arthur H. Compton was an American physicist who won the 1927 Nobel Prize for Physics for discovering and explaining changes in x-ray wavelengths resulting from x-ray collisions with electrons (the so-called Compton effect). In 1922, this important discovery confirmed the dual nature (wave and particle) of electromagnetic radiation. A Ph.D. from Princeton University, Compton held many prominent positions, including professor of physics at The University of Chicago and chairman of the committee of the National Academy of Sciences that studied the military potential of atomic energy. His position on that committee made Compton instrumental in initiating the Manhattan Project, which resulted in the first atomic bomb.

Previous award recipients include Nikolai Vinokurov and Klaus Halbach (1995); Philip M. Platzman and Peter Eisenberger (1997); Donald H. Bilderback, Andreas K. Freund, Gordon S. Knapp, and Dennis M. Mills (1998); Sunil K. Sinha (2000); Wayne A. Hendrickson (2001); Martin Blume, L. Doon Gibbs, Denis McWhan, and Kazumichi Namikawa (2003); Günter Schmahl and Janos Kirz (2005); Andrzej Joachimiak and Gerold Rosenbaum (2007); and Gerhard Grübel, Simon Mochrie, and Mark Sutton (2009).

The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science. The APS is the source of the Western Hemisphere’s brightest high-energy x-ray beams for research in virtually every scientific discipline. More than 3,500 scientists representing universities, industry, and academic institutions from every U.S. state and several foreign nations visit the APS each year to carry out applied and basic research in support of the BES mission to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels in order to provide the foundations for new energy technologies and to support DOE missions in energy, environment, and national security.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.